Server virtualization is a technology that abstracts physical resources of a server into logical resources, and allows one server to become multiple independent virtual servers, or allows several servers to be used as one server. Server virtualization is no longer limited to a physical boundary; instead, hardware is changed into a dynamically manageable resource pool. Thereby, resource utilization is increased, system management is simplified, and server integration is implemented.
Normally, server virtualization is implemented in a manner of virtualizing a server into a virtual machine (VM). A virtual machine is a complete computer system simulated by software. It has complete hardware system functions and runs in a completely isolated environment. In some cases, a virtual machine migration technology needs to be applied. The virtual machine migration technology may instantly migrate a whole running virtual machine from one server to another server by using complete virtualization of a server, storage, and network connection.
An important requirement of virtual machine migration is that services should not be interrupted. For this purpose, before virtual machine migration is completed, corresponding virtual machine parameters needs to be configured on a server at an in-migration location of the virtual machine, namely, a destination server, and an upstream network device of the destination server. The virtual machine parameters may include static configurations and dynamic information. Static configurations are virtual machine parameters that do not change dynamically with time. These configurations are not time-sensitive, and services running on the VM may not be affected so long as the configurations are completed before the VM migration is completed. In addition to the static configurations, some dynamic information is generated on an upstream network device of the virtual machine according to a network traffic volume or state. The dynamic information refers to virtual machine parameters that may change dynamically with time. For example, a firewall or a device having a firewall function may store a transmission control protocol (TCP) connection table for describing necessary information of a TCP connection, such as a source Internet protocol (IP) address and a destination IP address, a source port and a destination port, a connection state, and a current sequence number. For another example, an upstream network device that enables a dynamic host configuration protocol (DHCP) snooping function needs to have a DHCP snooping table, and some upstream network devices may further store accumulative data, such as the number of TCP connections already established by a VM and the number of packets sent by the VM. The dynamic information cannot be configured in advance. However, if the dynamic information is not configured correctly, services running on the VM may be directly affected. For example, if the firewall lacks a TCP connection table, packets of services running on the VM may be discarded by the firewall.
Normally, when the virtual machine is migrated, only static configurations of the virtual machine parameters are migrated, and dynamic information is reacquired by the upstream network device of the virtual machine after the virtual machine is migrated. Before the dynamic information is reacquired, services on the virtual machine may be interrupted.